Device for regulating medium flow, in particular the flow of air of a radial fan

ABSTRACT

Device for regulating medium flow of a radial fan, comprising means for reducing the active surface of a blade wheel or the like for generating said flow. The device consists of a cylindrical tubular member bearing against the inward radial edges of the blades and rotating therewith. The member extends axially of the blades to impede the outward flow along the blades between the inner and outer axial ends of the member. The regulation is effected by selectively positioning the outer end of the member at a point along the length of the blades. The member may extend to the inner axial end of the blades and effect regulation by varying the axial length of the member, or the member may be of a fixed length and effect regulation by varying the axial position of the member.

United States Patent [191 Sjoqvist et al.

[ 51 Jan. 21, 1975 DEVICE FOR REGULATING MEDIUM FLOW, IN PARTICULAR THE FLOW OF AIR OF A RADIAL FAN [75] Inventors: Lennart Sjoqvist, Jonkoping; Stig Lidbamn, I-Iuskvarna, both of Sweden [73] Assignee: AB Svenska Flakttabriken, Nacka,

Sweden [22] Filed: Feb, 14, 1973 [21] Appl. No.: 332,263

[30] Foreign Application Priority Data Feb. 25, 1972 Sweden 2335/72 [52] US. Cl. 415/157 [51] Int. Cl F04d 27/00 [58] Field of Search 415/157, 141, 156, 158

[56] References Cited UNITED STATES PATENTS 1,053,154 2/1913 Campbell et al 415/157 1,556,771 10/1925 Dupont 415/157 1,834,959 12/1931 May 1,846,379 2/1932 Anderson..... 2,078,580 4/1937 Moore 2,430,225 11/1947 Hagler 2,542,121 2/1951 Earl 415/157 FOREIGN PATENTS OR APPLICATIONS Primary Examiner-Henry F. Raduazo Attorney, Agent, or Firm--Dorfman, Herrcll and Skillman [57] ABSTRACT Device for regulating medium flow of a radial fan, comprising means for reducing the active surface of a blade wheel or the like for generating said flow. The device consists of a cylindrical tubular member bearing against the inward radial edges of the blades and rotating therewith. The member extends axially of the blades to impede the outward flow along the blades between the inner and outer axial ends of the member. The regulation is effected by selectively positioning the outer end of the member at a point along the length of the blades. The member may extend to the inner axial end of the blades and effect regulation by varying the axial length of the member, or the member may be of a fixed length and effect regulation by varying the axial position of the member.

7 Claims, 6 Drawing Figures PATENIEDJANZI I915 3.861 .824

' sum 10F a TFI 6.1

PATENTEU M21 1915 SHEET 2 OF 3 DEVICE FOR REGULATING MEDIUM FLOW, IN PARTICULAR THE FLOW OF AIR OF A RADIAL FAN The present invention refers to a device constructed for the regulation of medium flow, in particular the flow of air of radial fans.

For example, radial fans are manufactured in various sizes and have parts with various dimensions. Thereby it is possible to make a rough selection which will be determined primarily by the maximum demand. The fine adjustment of the medium flow can then be made by changing-as a rule contacting-the area of intake and outlet of the fan cover or the motor output.

Such suggestions, however, generally have only theoretical value and are rejected for practical application, as such forms of adjustment are too complicated, expensive and bulky with too much reliance on specialists. There are also a number of undesirable secondary effects as a result of the aforesaid suggestions.

The objective of the invention is to create a regulating device in the field related above in order to eliminate said disadvantages.

This objective can be realized by that a device for regulating medium flow, in particular the flow of air of a radial fan, which consists of a body placed in the medium passage and whose sectional area is reduced, wherein this body is placed inside of or in the immediate vicinity of the device for generating medium flow, e.g. a blade wheel, and that the body is designed and placed in such a way that it reduces the active surface of said device.

Other characteristics of and advantages with the invention are presented in the following detailed description, which makes reference to the attached drawings. In these FIG. 1 shows a regulating device installed in a radial fan, according to the invention, in a schematic, axial, diametrical section.

FIG. 2 shows a device similar to the prior art fans in which a regulating device is installed in the casing.

FIGS. 3-4 show similar views of modified regulatory devices, according to the invention.

FIG. 5 shows the regulating characteristic of a device, according to the invention, with a variable width as in FIGS. 1 and 3, and

FIG. 6 shows regulating characteristic for a device, according to the invention with a constant width and a variable position as in FIG. 4.

In the drawings, 1 denotes the cover around radial fan 2 including electric motor 3, which is fastened to a radial wall with rotating flange 4, which is parallel and coaxially connected to rear wall 6 of blade wheel 5. 7 designates the open end of the blade wheel, i.e., inlet, and 8, the cover inlet, which is connected to the blade wheel inlet as an axial continuation of the same. The electric motor housing or any appertaining transmission can gear into the blade wheel, especially as truncated cone 11, which tapers towards its inlet.

According to the invention, inserted in wheel blade 5 is a regulating device for reducing air flow. This device has at least the approximate form of a ring and, according to FIG. 1, is tangent to the inner edges of blades 10, where it suitably jars against the rear wall of the wheel 6. Ring 9, as seen in FIG. 1, has the length (axial extension) in relation to the blades which is required to obtain the desired regulation characteristic (FIG. 3). Ring 9 having a certain length can for example be replaced by another ring 9 having a different length. Alternatively, several rings 9 of preferably different lengths can be put together to obtain the desired length. As a third alternative, a ring 9, which corresponds to the entire length of the blade wheel, can

. come with it and be cut at the time of assembly to the desired length as indicated in an accompanying table of regulating characteristics.

Ring 9 consists preferably of a slightly flexible or hard, elastic cellular plastic.

As only a portion of the length of the blade wheel functions as a fan, the power required is at the same time reduced, and regulation, thus, becomes more economical than in the case of the conventional method.

In FIG. 2 the regulating device is designed as cylinder 12, which is preferably lodged axially to slide into the cover inlet 8. By inserting cylinder 12 into the blade wheel at different lengths, different areas of operation for the blade wheel are obtained. In this manner, i.e. with the aid of the sufficiently long cylinder 12, infinitely variable adjustment is possible.

In FIG. 3 an alternative similar to the preceding is shown, though with internal arrangement and alignment in the opposite direction. An expandable regulating device 13, which is ring-shaped, resembling a telescope, and pointed toward the blade wheel inlet 7, is attached to the rear wall 6 of the blade wheel. Of course, attachment is also possible at flange 4 or cone 11, or near inlet 7 in order to obtain a nonrotary model, so that expansion takes place in the direction of wall 6. Here also there is an infinitely variable adjustment.

The operative design, as seen in FIG. 4, is the result of a unique discovery. Tests have indicated that ringshaped regulation divice 14, resembling the one shown in FIG. 1 and having a length corresponding to just a small part, e.g., between 20 percent and 50 percent, of the length of the blade wheel, can be placed in various axial positions, and, inspite of its own dimensions remaining unchanged and an unchanged total active area for the blade wheel, accounts for a variable regulation characteristic covering a relatively large scale, as is indicated in FIG. 6, which shows the regulation characteristic for the operative design seen in FIG. 4. This regulation characteristic is amazingly similar to the one shown in FIG. 5, which is based on differing lengths for the regulating device.

Accordingly, the design shown in Flg. 4 is as simple as it is effective. Each fan can be equipped with such a device, which is provided, for example, with such a length that the greatest possible margin of regulation is obtained. Then it is possible to remove the device entirely in order to obtain a maximal air flow or set the device in the axial position corresponding to the desired regulation characteristic. Here, too, there is infinite adjustment within the existing scale range.

According to the invention, the regulating device in its most simple form can be manufactured at minimal cost and, nevertheless, provide maximal performance.

Of course, there are special cases where an exchange between various long rings and various thick (measured radially) ones, too, is possible.

The designs described above and in the drawings are to be considered only as nonrestricted examples, which can be modified, combined or supplemented as wished within the scope of the invention and pursuant to patent claims. The regulated medium can be any gas, fluid or, for example, a powder-gas mixture. It is also possible to propel the fan, etc. by completely different means. In connection with the principle as illustrated in FIG. 4 it is even possible to envisage a plant regulating device which is adapted to utilize a blade wheel, for example, or something similar, which can also be opened from both sides in special cases.

The characteristic structure of the present invention includes a radial fan wheel mounted for rotation about an axis in a fan casing having an axial inlet. The fan wheel comprises a series of generally radially disposed blades mounted on an inner radial wall and extending outwardly therefrom generally parallel to the axis whereby upon rotation of said wheel air or other medium is drawn into the casing through the inlet and is caused to flow radially outward across said blades. The capacity of the fan wheel is adjusted by disposing a cylindrical tubular element bearing against the inward radial edges of the blades and rotating therewith. The member is of lesser axial length than the blades and the capacity of the fan is regulated by selectively positioning the outer end of the member at a point along the length of the blades, the greater distance from the inner radial wall of the wheel the smaller the flow generated by the wheel. in FIG. 1, the axial length of this cylindrical member is preselected to cause the inner end of the axial member to abut the inner wall of the wheel to predetermine the capacity of the fan. In FIG. 3, the tubular member is telescopically extendable to adjust the axial length of the tubular member to permit variation in the capacity by varying the axial length. In FIG. 4, a tubular member is of fixed length and is slidable axially to adjust the capacity in accordance with the spacing of the member from the inner wall. Preferably, the blade wheel has a truncated conical projection projecting from the inner wall toward the inlet within the series of blades. The conical projection is adapted to house transmission mechanism for rotating the blade wheel on its axis at a predetermined speed. In this fashion, a fine adjustment of the capacity of the fan wheel may be accomplished with the use of a standard assembly of wheel parts including the inner wall, the blades, the casing, etc., the adjustment of the capacity being accomplished by selectively positioning the outer axial end of the tubular member at a point along the length of the blades.

We claim:

1. A device for regulating medium flow comprising a casing having a fan wheel mounted therein for rotation about a central axis, said casing having an axial inlet for the medium, said fan wheel having a radial inner wall confronting said inlet and mounting a circle of gener- Y ally radially disposed blades extending axially from said wall toward said inlet in surrounding relation thereto, whereby upon rotation of said wheel, said blades effect flow of the medium through said inlet and radially outward across said blades, said blades having inner radial edges disposed in an imaginary cylindrical surface coaxial with said fan axis, andmeans for regulating the flow capacity of said wheel comprising a substantially cylindrical hollow tubular elastic ring member having an axial length less than the axial length of said blades and mounted for rotation with said fan wheel. the cylindrical surface coinciding with the imaginary cylindrical surface within said blade circle to frictionally bear against the inner radial edges of said blades, adapted to be displaced along the inner edges of the blades throughout their length whereby the capacity regulation is effected by selectively positioning the outer end of the member at a point along the length of said blades to provide a limited flow area between the outer end of said member and the inlet radially outward across said blades.

2. A device according to claim 1 wherein said cylindrical tubular member extends into abutting relation with the radial inner wall of said wheel.

3. A device according to claim 2 wherein said cylindrical tubular member comprises a series of telescoping rings to afford adjustment of the position of the outer axial end of said tubular member.

4. A device according to claim 1 wherein said cylindrical tubular member has an inner axial end spaced from said inner radial wall to provide a complementary limited flow area between the inner end of said member and said radial wall.

5. A device according to claim 4 wherein said ring has an axial length between 20 percent and 50 percent of the length of the blades and is slidable axially of said wheel to assume various positions to change the regulating characteristics.

6. A device according to claim 1 wherein said tubular member consists of a slightly flexible or hard elastic cellular plastic.

7. A device according to claim 1 wherein said blade wheel has on its inner radial wall an outwardly projecting truncated cone tapering toward the inlet of the casing for cooperating with said cylindrical tubular member to regulate the capacity of the device.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,86l,824 Dated January 21, 1975 Inventor) Lennart Sjoqvist and Stig Lidhamn It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the list of inventors in the heading, the second inventor should be correctly spelled as --Stig Lidhamn--;

Column 1, line 12, "contacting" should read --contracting--;

Column 2, line 34, "divice" should read -device--.

Signed and sealed this 1st day of April 1575.

(SEAL) fittest:

q v C. I-EARSHALL DAM! 1 .1 n C MASON Commissioner of Patents attesting Officer and Trademarks FORM PO-IOSO (10-65) USCOMM-DC 60376-P69 u.s. covnmuu'r nun'rmc orrlc: mo o-su-au. 

1. A device for regulating medium flow comprising a casing having a fan wheel mounted therein for rotation about a central axis, said casing having an axial inlet for the medium, said fan wheel having a radial inner wall confronting said inlet and mounting a circle of generally radially disposed blades extending axially from said wall toward said inlet in surrounding relation thereto, whereby upon rotation of said wheel, said blades effect flow of the medium through said inlet and radially outward across said blades, said blades having inner radial edges disposed in an imaginary cylindrical surface coaxial with said fan axis, andmeans for regulating the flow capacity of said wheel comprising a substantially cylindrical hollow tubular elastic ring member having an axial length less than the axial length of said blades and mounted for rotation with said fan wheel, the cylindrical surface coinciding with the imaginary cylindrical surface within said blade circle to frictionally bear against the inner radial edges of said blades, adapted to be displaced along the inner edges of the blades throughout their length whereby the capacity reGulation is effected by selectively positioning the outer end of the member at a point along the length of said blades to provide a limited flow area between the outer end of said member and the inlet radially outward across said blades.
 2. A device according to claim 1 wherein said cylindrical tubular member extends into abutting relation with the radial inner wall of said wheel.
 3. A device according to claim 2 wherein said cylindrical tubular member comprises a series of telescoping rings to afford adjustment of the position of the outer axial end of said tubular member.
 4. A device according to claim 1 wherein said cylindrical tubular member has an inner axial end spaced from said inner radial wall to provide a complementary limited flow area between the inner end of said member and said radial wall.
 5. A device according to claim 4 wherein said ring has an axial length between 20 percent and 50 percent of the length of the blades and is slidable axially of said wheel to assume various positions to change the regulating characteristics.
 6. A device according to claim 1 wherein said tubular member consists of a slightly flexible or hard elastic cellular plastic.
 7. A device according to claim 1 wherein said blade wheel has on its inner radial wall an outwardly projecting truncated cone tapering toward the inlet of the casing for cooperating with said cylindrical tubular member to regulate the capacity of the device. 